How are American engine mfgs able to make high HP with simple designs? - Page 4
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  1. #61
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    Quote Originally Posted by goldenfab View Post

    Everything I have heard from old timer mechanics is the fuel of today is terrible in comparison with the past.
    Only good thing nowadays is E85 or 85% ethanol. Pretty common pump gas here in Europe.
    Equivalent to about 112 american octane and not sensitive for advance.
    In a modern 4-valve combustion chamber 15:1 or 16:1 is probably ok compression ratio.
    Or 60psi boost at 7:1 compression

  2. #62
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    Quote Originally Posted by CalG View Post
    No need to wonder.

    OHC, Valve in head and L heads were popular all around the same time, but I suppose one could make a case for a progression.

    "If you want to lean something new, read an old book."
    My impression is that everything was tried all at the same time. Pre WWI cars have an unbelievable range of innovative designs from the simplest to the incredibly complex. Here's a 1912 Peugeot 7.6 litre DOHC 4 valve that beat engines twice it's size and won Indy in 1913. Some of the earliest IC engines were OHVs, it seems to me that flathead engines were an effort to simplify things, not the starting point.

    p4.jpg

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  4. #63
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    Quote Originally Posted by 72bwhite View Post
    wasn't the some law that every town had to have a Telegraph and or Telephone road
    Perhaps, but Telegraph in Detroit was the "unofficial" testing and proving grounds for just about every 60s and 70s American muscle car.
    Certainly not officially sanctioned by the car companies but a lot of testing against the competition occurred at nights on this road which would result in tweaking things back at the factory before a car or powertrain went into full production.
    A different era.

    One word describes why you can make so much more power now......Computers.
    Look at a old fuel injection setup and a new one, look at ignition curves now and an old mechanical distributor.....computer control.
    Then there is the computer simulation and trial of many designs which earlier meant building one, testing, guessing, building again.
    Bob

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    Some supporting facts from owning one LeMans engine program, and then getting smart and leasing engines from others, with a side note from small airplanes...

    LeMans cars...

    1. They all had impressive power-to-weight given the rules, air intake restrictions, spec fuel, etc. And in the much-lighter-than-any-street cars they were run in, they'd smoke most muscle cars. Remember, we raced against track versions of Ferraris, Porsches, GT40s. The acceleration differences could be stunning.

    2. They all required very elaborate warmups early in the day. Think a heater and pump running pre-warmed coolant through the engine for 30 minutes before it was started the first time. Yes, by the rules, the driver starts the car, by him/her self, sitting a the wheel. But that's not how it works for the warmup you don't see before the car comes out of the garage before the race. (This can't apply to say the World of the Outlaws, where they do engine changes on very short notice.... Wonder how that works... Same for drag racing?)

    3. Even LeMans engines aren't normally built to last 24 hours - those are special builds....

    I'm sure F1 is pretty similar, if not more extreme.

    As for small plane engines - well various regulatory and liability issues have caused their development to be kind of stuck, but their biggest claim to fame is very high reliability in a high consequence environment, at 80% power all the time, with 100% used for real on purpose every flight (that whole taking off bit...)

    If you had to drive your street car at 100% throttle for the first 5 minutes of every trip, followed by 80% for the rest of the trip, your street car engine would need lots more attention too.

  6. #65
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    Quote Originally Posted by bryan_machine View Post
    If you had to drive your street car at 100% throttle for the first 5 minutes of every trip, followed by 80% for the rest of the trip, your street car engine would need lots more attention too.
    Thats exactly why they go over an aircraft engine so meticulously before every flight.

    As to the higher compression ratios I alluded to previously, it is why the power numbers are higher in todays car engines. Those higjer compression ratios are only possible because of computer controlled fuel , valve timing , aluminum heads and ignition. Together they adjust fuel air and timing so it can take advantage of the higher ratio. Without the computer , good luck.

    With direct fuel injection they can literally wait until the piston is just past tdc to prevent pre ignition, before charging the cylinder with fuel. Meaning 15 to 1 or more CR is no problem.

    Just my two cents worth.


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